Following the typical pattern

Here is the typical pattern for interacting with a relational database:

Define a Record, Handler, or external type and include annotations. For a Record type, you might retrieve details automatically from a database management system.

Declare a variable that is based on the defined type. Your code will copy data between the database and that variable.

Declare variables to represent the SQL data sources. Each data source is a connection or a result set.

Configure EGL statements that reference the variables that you declared. For each statement, rely on the SQL code that is provided for you or customize that code.

Defining a Record type

/*
* The annotations help to define the default SQL code when
* a record of this type is used in a given EGL statement:
* -- Table refers to the table being accessed. If Table is not supplied,
* the name of the Record type is assumed to be the table name.
* -- Column refers to the column being accessed. If Column is not supplied,
* the name of the field is assumed to be the name of the column.
* -- ID indicates that the field and its value are set to equal
* in the default SQL INSERT statement (for an EGL add statement) and
* in the default SELECT statement (for an EGL get or open statement).
*/
Record PaymentRec { @Table {name="PAYMENT"}}
paymentId int{@ID, @GeneratedValue, @Column { name="PAYMENT_ID"}};
description string?{ @Column { name="DESCRIPTION"}};
amount decimal(10,2){ @Column { name="AMOUNT"}};
End

Getting a row

Here is code for getting a record:

function getCustomer(someId String in} returns (Customer)
ds SQLDataSource?{@resource {}};// declares a data source that will use binding name "ds" (since a name is not specified)
aCust Customer;// declares and empty customer record
get aCust from ds using(someId);// gets the record in the table that has a key value of someID and populates the customer record
get aCust from ds using(someId) with #sql{// alternative approach for getting a single record (allows for customizing the SQL)
SELECT *
FROM CUSTOMER
WHERE id =?};
vals Dictionary;// declares a new dictionary
get vals from ds using(someId) with #sql{// alternative approach for getting a single record (does not require a Record definition)
SELECT *
FROM CUSTOMER
WHERE id =?};// creates a key/value pair in the dictionary for each column in the result setreturn(aCust);
end

Getting multiple rows with one EGL statement

function getCustomer(} returns (Customer[])
ds SQLDataSource?{@resource {}};// declares a data source that will use binding name "ds" (since a name is not specified)
custs Customer[];// declares a new dynamic array of customer records
get custs from ds;// populates the array with a Customer record for each row in the result set
get custs from ds with #sql {
select * from customer where state ='CO'};// populates the array, but with a limited set of Customer records
state String="CO";
get custs from ds using(state) with #sql {
select * from customer where state =?};// parameterized version of the previous example
end

Looping through an SQL result set

function loopCust()
ds SQLDataSource?{@resource{uri ="binding:myDB"}};// declares a new data source
rs SQLResultSet?;// declares a new result set
open rs from ds with #sql{// opens a result set using the specified SQL query
SELECT * FROM CUSTOMER
};
myCust Customer;//Loop through results and write out customer namewhile(rs.getNext())
get myCust from rs;
Syslib.writeStdOut("Customer name: "+ myCust.name);
end
end